Motor control and nonword repetition in specific working memory impairment and SLI

PURPOSE:: Debate around the underlying cognitive factors leading to poor performance in the repetition of nonwords by children with developmental impairments in language has centered around phonological short-term memory, lexical knowledge, and other factors. This study examines the impact of motor control demands on nonword repetition in groups of school children with specific impairments in language, working memory, or both. METHOD:: Children repeated two lists of nonwords matched for motoric complexity either without constraint or with a gummi bear bite block held between their teeth. The bite block required motoric compensation to reorganize the motor plan for speech production. RESULTS:: Overall, the effect of the biomechanical constraint was very small for all groups. When analyses focused only on the most complex nonwords, children with language impairment were found to be significantly more impaired in the motorically constrained nonword repetition task than the typically developing group. In contrast, working memory difficulties were not differentially linked to motor condition. CONCLUSIONS:: These findings add to the growing evidence that there is a motoric component to developmental language disorders. The results also suggest that the role of speech motor skill in nonword repetition is relatively modest. Copyright © 2013 Wolters Kluwer Health | Lippincott Williams & Wilkins

On the X-ray variability of magnetar 1RXS J170849.0-400910

We present a long-term X-ray flux and spectral analysis for 1RXS J170849.0-400910 using Swift/XRT spanning over 8 years from 2005-2013. We also analyze two observations from Chandra and XMM in the period from 2003-2004. In this 10-yr period, 1RXS J170849.0-400910 displayed several rotational glitches. Previous studies have claimed variations in the X-ray emission associated with some of the glitches. From our analysis we find no evidence for significant X-ray flux variations and evidence for only low-level spectral variations. We also present an updated timing solution for 1RXS J170849.0-400910, from RXTE and Swift observations, which includes a previously unreported glitch at MJD 56019. We discuss the frequency and implications of radiatively quiet glitches in magnetars.Comment: 9 pages, 2 figures, accepted for publication in Ap

Mathematical Abilities in Children with Developmental Language Disorder

Purpose. The present paper provides a scoping review of the literature on mathematical abilities in developmental language disorder (DLD). Children with DLD typically struggle with learning in school, however the mechanism by which DLD impacts academic success is unclear. Mathematics involves demands in the multiple domains, and therefore holds potential for examining the relationship between language and academic performance on tasks mediated by verbal and non-verbal demands. Methods. A scoping review was performed via computerized database searching to examine literature on mathematics and DLD. The 21 papers meeting inclusion criteria compared children with typical development or DLD on various tasks measuring numerical cognition. Results. Children with DLD consistently performed below peers with typical development on number transcoding, counting, arithmetic, and story problem tasks. However, performance was similar to peers with typical development on most number line, magnitude comparison, and conceptual mathematics tasks. Conclusions. The findings suggest a relationship between DLD and mathematics was characterized by more detrimental performance on tasks with higher verbal demands. Results are discussed with respect to typical academic curricula and demonstrate a need for early identification and intervention in DLD to optimize academic outcomes

Green Bank Telescope and Swift X-ray Telescope Observations of the Galactic Center Radio Magnetar SGR J1745-2900

We present results from eight months of Green Bank Telescope 8.7-GHz observations and nearly 18 months Swift X-ray telescope observations of the radio magnetar SGR J1745-2900, which is located 2.4" from Sgr A*. We tracked the magnetar's radio flux density, polarization properties, pulse profile evolution, rotation, and single-pulse behavior. We identified two main periods of activity in SGR J1745-2900. The first is characterized by approximately 5.5 months of relatively stable evolution in radio flux density, rotation, and profile shape, while in the second these properties varied substantially. Specifically, a third profile component emerged and the radio flux increased on average, but also became more variable. Bright single pulses are visible and are well described by a log-normal energy distribution at low to moderate energies, but with an excess at high energies. The 2-10 keV flux has decayed steadily since the initial X-ray outburst, in contrast with the radio flux. Our timing analysis includes Green Bank Telescope, Swift, and NuSTAR data. When we include the X-ray data in our analyses, we find that SGR J1745-2900 exhibited a level of timing noise unprecedented in a radio magnetar, though an analysis of only the radio data indicates timing noise at a level similar to that observed in other radio magnetars. We conclude that, while SGR J1745-2900 is similar to other radio magnetars in many regards, it differs by having experienced a period of relative stability in the radio band that now appears to have ended, while the X-ray properties have evolved independently.Comment: Submitted to ApJ; 10 pages (emulateapj style), 6 figures, 1 tabl

The 2016 outburst of PSR J1119-6127: cooling & a spin-down dominated glitch

We report on the aftermath of a magnetar outburst from the young, high-magnetic-field radio pulsar PSR J1119-6127 that occurred on 2016 July 27. We present the results of a monitoring campaign using the Neil Gehrels Swift X-ray Telescope, NuSTAR, and XMM-Newton. After reaching a peak luminosity of ~300 times the quiescent luminosity, the pulsar's X-ray flux declined by factor of ~50 on a time scale of several months. The X-ray spectra are well described by a blackbody and a hard power-law tail. After an initial rapid decline during the first day of the outburst, we observe the blackbody temperature rising from kT = 0.9 keV to 1.05 keV during the first two weeks of the outburst, before cooling to 0.9 keV. During this time, the blackbody radius decreases monotonically by a factor of ~4 over a span of nearly 200 days. We also report a heretofore unseen highly pulsed hard X-ray emission component, which fades on a similar timescale to the soft X-ray flux, as predicted by models of relaxation of magnetospheric current twists. The previously reported spin-up glitch which accompanied this outburst was followed by a period of enhanced and erratic torque, leading to a net spin-down of $\sim3.5\times10^{-4}$ Hz, a factor of ~24 over-recovery. We suggest that this and other radiatively loud magnetar-type glitch recoveries are dominated by magnetospheric processes, in contrast to conventional radio pulsar glitch recoveries which are dominated by internal physics.Comment: Submitted to Ap

How does iron interact with sporopollenin exine capsules? An X-ray absorption study including microfocus XANES and XRF imaging

Sporopollenin exine capsules (SECs) derived from plant spores and pollen grains have been proposed as adsorption, remediation and drug delivery agents. Despite many studies there is scant structural data available. This X-ray absorption investigation represents the first direct structural data on the interaction of metals with SECs and allows elucidation of their structure–property relationships. Fe K-edge XANES and EXAFS data have shown that the iron local environment in SECs (derived from Lycopodium clavatum) reacted with aqueous ferric chloride solutions is similar to that of ferrihydrite (FeOOH) and by implication ferritin. Fe Kα XRF micro-focus experiments show that there is a poor correlation between the iron distribution and the underlying SEC structure indicating that the SEC is coated in the FeOOH material. In contrast, the Fe Kα XRF micro-focus experiments on SECs reacted with aqueous ferrous chloride solutions show that there is a very high correlation between the iron distribution and the SEC structure, indicating a much more specific form of interaction of the iron with the SEC surface functional groups. Fe K-edge XANES and EXAFS data show that the FeII can be easily oxidised to give a structure similar to, but not identical to that in the FeIII case, and that even if anaerobic conditions are used there is still partial oxidation to FeIII

Heavy metal removal from water/wastewater using fly-ash derived zeolites

Heavy metal pollution in water has been a growing concern over the years and is under strict regulations from legislative bodies. Adsorption is an efficient and cost-effective way of metal removal from polluted water. Therefore, industries are seeking cheaper, environmentally friendly, easily accessible and efficient adsorbents for treating their effluents of heavy metals before disposal into surface waters. Activated carbon, the most popular commercial adsorbent, has become more expensive due to increasing demand, high cost of production and regeneration. Natural zeolites are not commercially available in most parts of the world while synthetic zeolites, produced from chemical precursors, are also expensive. Fly-ash derived zeolites provide a cheaper alternative as they can be synthesized from a waste product. Initial research on fly-ash derived zeolite (Sodium P/ Gismondine) NaP1 has highlighted the potential for heavy metal removal from wastewater under different conditions without a clear understanding of the metal uptake mechanism and within industrial conditions (i.e. pelleting, multi-element adsorption with pellets and regeneration). Hence, there is limited information to adapt this material for industrial wastewater treatment. This research aims to provide a thorough understanding of the characteristics of fly-ash derived NaP1 to harness its potential use in industrial wastewater treatment. Results from this study indicate metal uptake capacities of NaP1 for zinc (34 mg/g) and lead (192 mg/g) were higher than other fly-ash derived NaP1, commercial activated carbon and clinoptilolite. In competitive adsorption, the metal selectivity for NaP1 followed the order Pb2+>Cu2+>Zn2+, while multi-element removal efficiency was identified in the order NaP1 powder > NaP1 pellet > commercial 3A pellet. Langmuir model and pseudo-second order kinetic model fitted best for all elements. The rate of metal uptake was fast and occurred in 15 min for all metals in contact with powder. The rate-determining step is controlled by diffusion of hydrated metals through microporous channels of NaP1. Copper regeneration from NaP1 was best achieved using Na and K salts at pH 5 and 22 ± 2 °C. NaCl and KCl solutions produced ~ 30% copper regeneration (representing 2.6 mg/g NaP1) while copper recovery with regeneration solutions was in the order K+>Na+>H+. After pelleting without binder, adsorption experiments showed a type II isotherm with an H3 hysteresis loop, indicating the presence of unrestricted monolayer – multilayer adsorption. The mean pore diameter for NaP1 pellet was 14.3 ± 0.275 nm compared to 10.95 ± 0.069 nm for powder NaP1. However, BET area of NaP1 pellets was 28% lower than the powder form. This research has demonstrated the viability of NaP1 for heavy metal removal from wastewater. Fly-ash waste from coal power plants could be sourced in creating zeolite NaP1 instead of dumping them into landfills and enhancing secondary pollution. Secondly, NaP1 can be converted into pellets without a binder for industrial use since it displays quick kinetics of 15 mins for metal uptake. Furthermore, NaP1 works efficiently at pH 5 and can be regenerated easily with eluents such as NaCl and KCl